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Let the Obesity-Drug Wars Begin

Arena gets a solid endorsement from the FDA advisory panel.

Arena Pharmaceuticals' (Nasdaq: ARNA) lorcaserin advisory committee win wasn't as good as VIVUS' (Nasdaq: VVUS) 20-2 endorsement of its obesity drug, but I'd put the 18-4 vote in the "good enough" column. Even if you count the copout abstention that one panelist cast as a negative, it's still a pretty solid endorsement, and by a higher margin than I was expecting.

The agency doesn't have to follow the committee's recommendation. But given the generally positive briefing documents for the committee, which are written by the FDA reviewers, Arena's chances for approval look pretty good to me.

The one area where the FDA seemed iffy was the potential for lorcaserin to cause problems with heart valves, but only one of the cardiologists on the panel voted against the approval. It looks like any potential heart issues can be taken care of in a post-marketing study, unlike Orexigen's (Nasdaq: OREX) Contrave, which had a strong enough signal to require a pre-approval study.

Two of the "no" votes were cast by toxicologists, which is a little worrisome since it seemed like the potential to cause cancer had been put to rest by the agency. The big unknown is how much influence the outside toxicologists on the panel will have on changing the opinions of the internal toxicologists reviewing the drug. An approval certainly isn't a sure thing. Then again, it never is.

Arena's PDUFA date is June 27, which puts it first in line after the decision on VIVUS' Qnexa was delayed to work out the details of the REMS. It seems possible that lorcaserin will also be delayed for the same reason. The company hasn't submitted a REMS, but if the FDA goes along with some panelist's recommendation that doctors perform routine heart checks of patients taking lorcaserin, it would likely need to be regulated through a REMS. Discussions on post-marketing requirements could also delay an approval.

But investors shouldn't get hung up on who gets approved first. Neither company looks like they'll be ready to launch when the drug is approved. VIVUS doesn't have a marketing partner in place, and Arena and its marketing partner Eisai might have to wait four to six months for DEA scheduling if lorcaserin is deemed a controlled substance.

The REMS -- or lack thereof if Arena doesn't get one -- might ultimately affect sales, though. As we've seen with other drugs -- the bioscan requirement for Spectrum Pharmaceuticals' (Nasdaq: SPPI) Zevalin, for instance -- making doctors jump through hoops can hold down sales.